I've got a data entry HTML page with two embedded forms so that users can enter data to two different forms from one place within my application.  

However form 2 has look up fields linked to records in form 1 

When a user enters a new record in form 1, I want to update the dropdown lookup fields in form 2 so that the new data is added to the choices. 

In other words, how do you force an embedded form to refresh from an HTML page?

Many thanks